A user may perform an operation on a touch panel of a mobile electronic device at an initial brightness of the touch panel. If the user performs repeated operations on the touch panel, the initial brightness may be maintained throughout the repeated operation. However, brightness surrounding the touch panel may affect visibility of the touch panel. For example, when the user operations on the touch panel are being performed repeatedly while the user moves the mobile electronic device from a bright location to a dark location, the touch panel is illuminated at the same luminance used in the dark location.